1. Field of the Invention
The present invention relates to a nozzle system for laser machining to be attached to an arm of a robot, and in particular to a nozzle system for performing a laser machining operation and a teaching operation to the robot.
2. Description of Related Art
There has been recently arose a need of three dimensional laser machining using a robot in an automobile industry and other industries. However, it is difficult and thus takes a long time to teach a three-dimensional laser machining operation to a robot and thus such laser machining operation tends to be avoided. It is possible to perform an off-line teaching operation using a teaching software, but there probably exists a slight displacement between a position of an imaginary workpiece expressed by positional data in the teaching software and a position of a real workpiece in actual machining because of a dimensional dispersion of a workpiece, etc.
Therefore, it is necessary to modify and correct the taught data after the off-line teaching operation using the teaching software. It has been proposed a method of determining an operation path using an analysis software for calculating teaching points based on images of a real workpiece captured by a CCD camera attached to a laser machining nozzle, for example as proposed Japanese Patent No. 2822315.
In the above method, there arises a problem that an operating region of a robot without interference with surroundings is narrowed because of the camera attached to an upper side of the laser machining nozzle. Thus, it is necessary to put further restriction on the operating region of the robot, which is quite cumbersome and lowers efficiency of the teaching operation.
The above problem will be specifically described referring to FIG. 1, which shows a laser machining nozzle as proposed in Japanese Patent No. 2822315. In FIG. 1, a machining nozzle 1 has a semi-transparent mirror 5 and lenses 6, 7 inside. An optical fiber 2 for supplying a laser beam for machining is connected to the machining nozzle 1 on a lateral side thereof to direct the laser beam to the semi-transparent mirror 5.
The laser beam supplied from the optical fiber 2 is mostly reflected by the semi-transparent mirror 5 arranged inclined at 45 degree with respect to an optical axis 3 (positioned at a center of a core of the optical fiber 2) of the laser beam, and converged by the lens 6 to form a conversing laser beam 4 to be impinged on a workpiece 15, as an object of laser machining.
On the other hand, the camera 18 for capturing images of the workpiece 15 is mounted on an upper side of the machining nozzle 1 so that an optical axis 10 of the camera coincides with the optical axis of the laser beam 4.
The lens 7 is provided for adjusting a lens system comprising the converging lens 6 and the lens 7 to have characteristics suitable for photographing by camera 8, when it is necessary. In the teaching operation, images captured by the camera 8 are sent through a cable 9 to an image processor (not shown) and the teaching points and related data including designation of type of motion of linear/circular arc are taught to the robot using the teaching software.
In the above described machining nozzle, there arises a problem in that the optical fiber 2 for supplying the laser beam has to be arranged at the lateral side of the machining nozzle 1 since the camera 8 is mounted at the upper side of the machining nozzle 1. Specifically, in the teaching operation, the optical fiber 2 connected to the lateral side of the machining nozzle 1 is moved with movement of the machining nozzle 1, so that an interference between the optical fiber 2 and the surroundings tends to occur. In order to surely avoid the interference, the operating range of the robot has to be greatly restricted to make it difficult to position the machining nozzle to a desired position/posture.
An object of the present invention is to provide a nozzle system for laser machining capable of easily performing a teaching operation of a three-dimensional path to a robot with an area of interference between the machining nozzle and surroundings in the teaching operation maintained substantially the same as that in an actual laser machining operation.
A nozzle system for laser machining of the present invention is for use in a state of being attached to an arm of a robot for performing a laser machining operation on an object and a teaching operation to the robot. The nozzle system may comprise a nozzle body unit having a lens system for converging a laser beam; an optical fiber supporting unit for supporting an optical fiber for supplying the laser beam to the nozzle body unit; and a camera supporting unit having a camera for capturing images of the object. According to one aspect of the present invention, the optical fiber supporting unit is attached to the nozzle body unit in performing the laser machining, and the camera supporting unit is attached to the nozzle unit in place of the optical fiber supporting unit in performing the teaching operation.
It is preferable to provide holding means for holding the optical fiber supporting unit or the camera supporting unit at a predetermined position with respect to the nozzle body unit detachably.
According to another aspect of the present invention, the camera supporting unit is substituted for the nozzle body unit to be positioned such that a machining point by the laser beam is covered by a visual field of the camera in performing the teaching operation. In this case, the camera supporting unit preferably has substantially the same dimension as the nozzle body unit.
The camera supporting unit may be positioned such that an optical axis of the camera coincides with an optical axis of the laser beam in performing the teaching operation.
The camera supporting unit may further have a light beam projector for projecting a patterned beam such as a spot beam and slit beams on the object.
According to the present invention, since the nozzle body unit and the optical fiber supporting unit are used in combination in performing an actual laser machining operation and the camera supporting unit having the camera dedicated for teaching is used in place of the optical fiber supporting unit and further the nozzle body unit in performing a teaching operation, an area of interference between the machining nozzle and surroundings in the teaching operation is maintained substantially the same as that in the laser machining and thus teaching operation to the robot can be easily performed with respect to a complicated three-dimensional object.